1. Field of the Invention
The present invention relates to a relay apparatus which relays communication between a water heater main body and a radio remote control unit, and more particularly, to a relay apparatus which establishes wire communication with the water heater main body and which establishes radio communication with the radio remote control unit.
2. Description of the Related Art
As a conventional water heater, since an indoor wiring operation of a remote control unit is unnecessary and installation is easy, and besides a remote control unit can easily be provided for an already installed water heater, there is a water heater in which a relay apparatus (master set) is connected to an outdoor water heater main body by a wire, and the water heater main body is remote-operated by radio communication of a radio remote control unit (slave set) through the relay apparatus from a room (e.g., Japanese Patent Application Laid-open No. 2005-328295).
A plurality of radio remote control units can be installed in a bathroom, a kitchen and the like, wherein a master set ID of the relay apparatus is registered in each radio remote control unit, and a slave set ID of each radio remote control unit is registered in the relay apparatus. With this configuration, radio communication between the radio remote control units and the relay apparatus is performed without causing interference with other devices.
The radio remote control unit is usually used for operating the water heater. In addition to this, the radio remote control unit can also display maintenance information of the water heater main body on a display section by specifying and operating a switch at the time of maintenance operation of the water heater main body (e.g., Japanese Patent Application Laid-open No. HEI09-280557). Such a radio remote control unit can freely be taken outside. Therefore, an operator of the maintenance operation takes the radio remote control unit outside, displays the maintenance information at an outside installation place of the water heater main body, and the operator can carry out a predetermined maintenance operation while seeing the maintenance information.
However, if none of the radio remote control units is registered in the relay apparatus, the maintenance information of the water heater main body is not displayed. In a case where the water heater main body is set outside of a house, the relay apparatus is connected to the water heater main body, but none of the radio remote control units is ID-registered, the maintenance information of the water heater main body cannot be seen for e.g. inspection on setting condition of the water heater main body.
Even if at least one of the radio remote control units is registered in the relay apparatus, the maintenance information of the water heater main body cannot be seen when no one stays in the house or the radio remote control unit is out of order or the battery is dead. If the operator cannot see the maintenance information of the water heater main body, he or she cannot carry out the maintenance operation of the water heater main body.
Thus, in preparation for such cases, another radio remote control unit can be separately prepared for maintenance operation. This radio remote control unit is ID-registered in the relay apparatus, and maintenance information of the water heater main body is obtained by operating this radio remote control unit. However, it is very troublesome to prepare another radio remote control unit only for the maintenance operation and to ID-register the radio remote control prepared for the maintenance operation. Further, it is necessary to delete the ID registration of the radio remote control in the relay apparatus after the maintenance operation is completed. Furthermore, where the operator doesn't know whether or not a radio remote control unit is used during the maintenance operation is carried out, it is uneconomical to separately prepare the radio remote control unit for the maintenance operation, which leads to an increase in the maintenance cost. Even when the radio remote control unit is separately prepared, if the full registrable number of radio remote control units are all registered in the relay apparatus, another radio remote control unit cannot be further ID-registered. Therefore, the operator cannot see the maintenance information in this case.